Continuous multiple core rolling mill train for producing rolled bar stock especially wire of heavy coil weights

ABSTRACT

A MULTIPLE CORE WIRE TRAIN FOR HEAVY COIL WEIGHTS WITH A RAPID TRAVEL SINGLE CORE ROUGHING GROUP AND A MULTIPLE CORE HEATING TROUGH FROM WHICH THE ROUGHING SECTIONS THAT ARE ROLLED DOWN TO THE USUAL BILLET DIMENSIONS OF AN EDGE LENGTH BETWEEN ABOUT 80 TO 100MM. ARE CONTINUOUSLY INTRODUCED INTO THE VACATED GROOVES OF THE FIRST MULTIPLE CORE ROLLING GROUPS. THE PASS CROSS SECTION IN THE SINGLE CORE ROUGHING GROUP MAY BE THEORETICALLY OF ANY SIZE DEPENDING ON THE NUMBER OF ROUGHING STANDS SO THAT BARS PRODUCED IN A CONTINUOUS CASTING OPERATION HAVING FOR EXAMPLE AN EDGE LENGTH OF 180MM. MAY BE ROLLED INTO WIRE IN A SINGLE PASS.

3,625,043 FOR PRODUCING COIL WEIGHTS $83 8 my mm K. J. NEUMANN LCONTINUOUS MULTIPLE CORE ROLLING MILL ROLLED BAR STOCK, ESPECIALLY WIREOF HEAVY Filed Nov. 13, 1969 United States Patent 3,625,043 CONTINUOUSMULTIPLE CORE ROLLING MILL TRAIN FOR PRODUCING ROLLED BAR STOCK,ESPECIALLY WIRE OF HEAVY COIL WEIGHTS Karl Josef Neumann and KlausNeumann, St. Ingbert (Saar), Germany, assignors to Moeller & NeumannG.m.b.H., St. Ingebert (Saar), Germany Filed Nov. 13, 1969, Ser. No.876,272 Claims priority, application Germany, Nov. 14, 1968, P 18 08822.7 Int. Cl. 1321b 1/18, 27/06, 41/00 US. Cl. 72-202 6 Claims ABSTRACTOF THE DISCLOSURE A multiple core wire train for heavy coil weights witha rapid travel single core roughing group and a multiple core heatingtrough from which the roughing sections that are rolled down to theusual billet dimensions of an edge length between about 80 to 100 mm.are continuously introduced into the vacated grooves of the firstmultiple core rolling groups. The pass cross section in the single coreroughing group may be theoretically of any size depending on the numberof roughing stands so that bars produced in a continuous castingoperation having for example an edge length of 180 mm. may be rolledinto wire in a single pass.

The invention relates to a continuous multiple core rolling mill trainfor producing rolled bar stock, particularly wire of heavy coil weights,comprising a furnace, a roughing group, an intermediate group and singlecore finishing groups. Although the invention has been developedprimarily for use with wire trains it may be applied advantageously alsofor medium and high quality steel trains. For the purpose of thisdisclosure the following description is directed specifically to thelayout of wire trains.

The following are the major influence factors which determine the levelof output of a wire train:

(a) number of cores (b) wire end speed (c) pass cross section (d) billetlength The number of cores cannot be increased at will due to thelimitations inherent in the equipment. With the four core wire rollingtrain an optimum operation seems to have been reached in view of theinfluence factor (a).

The wire end speed may be increased, but this is limited by the croppingshears and the coiler apparatus, so that one can state here also thatthe influence factor Wire end speed of about 50 m./ sec. while usingnormal shears and coilers represents at the present time an optimumoperation, at least when no risks are to be taken with regard tooperational safety.

The invention aims at an increase of production in the direction ofheavier core weights for which the influence factors pass cross sectionand billet length prevail. The billet length could be theoretically ofany size which may be realized already by welding together variousbillet lengths. However, this solution is excluded from the scope ofthis invention because it does not allow an easy multiple coreoperation. This leaves therefore the possibility of increasing thebillet length, but this has an unfavorable 3,625,043 Patented Dec. 7,1971 influence with respect to the furnace construction. Based oneconomic considerations the optimum furnace size lies today at a maximumbillet length of about 12 m.

In order to increase the coil weight in a wire train on the basis of theabove considerations there remains the possibility of increasing thepass cross-section. But particularly on this point the general opinionis that an optimum operation has been reached if one considers that eachincrease of the pass cross-section means an increase in the number ofpasses and according to the continuous flow principle a correspondinglydecreased input of the billets into the first stand of the roughinggroup. This causes an unfavorable influence on the heat consumption ofthe train because the travel time of the billets is increased and thusthe temperature difference between the front end and the rear end of thebillets becomes greater. It is thus obtained that the deformationresistance across the bar length is unequal and the rolling pressurechanges especially in the end stands during the passing of the bars sothat the tolerance maintenance of the end product becomes worse. Theclassical pass cross-section for multiple core wire trains liestherefore today at mm. square. In order to produce from this a coilweight of 1500 kp. the billets would have to have a length of 30 m.,which is completely impractical from the standpoint of the furnacebuilder. The pass cross-section would have to lie at about mm. squarewhich at a wire end speed of 50 m./sec. on the basis of the continuousflow principle would mean an input speed in front of the first stand ofthe roughing group of 0.075 m./sec. This low input speed is complete- 1yimpractical from the standpoint of heat economy. Even in that case thebar length would still have to be about 14.8 m., if one sets out for acoil weight of 1500 kp. a raw weight of the billet of 1550. Also withthis billet length the furnace would become fairly Wide and would haveto be provided with a complicated suspension ceilmg.

The classical multiple core wire trains operate for reasons of heateconomy directly out of the furnace so that with the low input speed ofthe billets into the first stand of the roughing group the end of thebillets is subjected to heat as long as possible. This means a certaindisadvantage in that the billets cannot be sprayed down before therolling process in order to remove scale.

The invention shows the way to provide in a multiple core continuousrolling mill train for the production of wire of heavy coil weightssubstantially independent of the pass cross-section, which could bepresumed to be impossible in view of what has been mentioned before. Thesolution of the problem which has been presented consists in that oneuses instead of a multiple core roughing group a single core rapidtravel roughing group preferably with an H-V arrangement of the stands,from which the roughing sections exit freely with an exit speed that islarger relative to the input speed determined by the continuous flowprinciple and the wire end speed of the multiple core intermediate groupby at least a multiple of the core number, wherein a heating devicewhich collects the freely exiting roughing sections and is locatedbetween a distributing guide and the intermediate group is pro-' vided,from which the roughing sections may be conducted in each case tovacated grooves of the intermediate group.

The single core operation of the roughing group according to theinvention allows first of all a free selection of the pass cross-sectionrelative to a conventional multiple core roughing group particularlywhen due to the H-V arrangement of the stands no twisting is required.With the increase of the pass cross-section one need merely increase thenumber of stands in the roughing group. The rapid travel of the singlecore roughing group which has to supply the grooves with roughingsections provides that due to the relatively high input of the billetsinto the roughing group one may discard the rolling out of the furnace.The billets may be completely freed of scale by a high pressurespray-down device before being introduced into the roughing group. Thehigh rolling speed of the roughing group reduces not only the influenceof the cooling water on the temperature of the roughing section but thesingle core arrangement of the roughing group presents also theadvantage of highest accuracy of the existing cross-sections and permitsin comparison with the multiple core roughing down operation lighterstands and smaller driving moments, because the required torques aresmaller. The heating device collecting the freely exiting roughingsections in front of the intermediate group now assures that the ends ofthe roughing section are heated up during the now slow input of theroughing sections into the grooves of the multiple core intermediategroup or are either kept warm or heated up further in order to preventduring the further intermediate and finishing rolling the temperaturedrop to be expected toward the rear end of the bar.

In this respect the heating device corresponds practically to thefurnace and the multiple core intermediate group to the roughing groupof a classical wire train which is supplied with the usual passcross-section of 80 mm. square. From this standpoint the inventionconsists of an arrangement which precedes the furnace and provides arational reduction of even the highest initial cross-section down to theclassical pass cross-section of 80 mm. square wherein thiscross-section, in consideration of a coil weight of 1500 kp. to beobtained according to what has been mentioned previously should be 30 m.long. There is no particular problem of building a heating trough ofthis length especially since it may be shorter than the length of theroughing sections and that it has to take up the roughing sections onlyup to a front end protruding beyond the furnace length since it is abasic requirement to heat up the rear bar end of the roughing sectionsupon entering the intermediate group.

It has been stated that the roughing group should operate with an exitspeed for the roughing sections which is larger relative to the inputspeed of the multiple core inter-mediate group determined by thecontinuous principle and the wire end speed by at least a multiple ofthe core number. It lies Within the scope of the invention that theroughing group may travel even faster if this is desired from thestandpoint of heat economy but in that case stoppages must be allowed inthe billet sequence of the roughing sections when the heating device isdesigned only for receiving a number of roughing sections in adjacentrelationship corresponding to the core number of the intermediate group,wherein the distributing guide receiving the heating device directs theroughing sections in adjacent relationship and in the exact direction ofthe grooves of the intermediate group. It is appropriate to provide amultiple core driving apparatus between the heating device and theintermediate group in order to continuously feed the roughing sectionsof the intermediate group wherein depending on the size of the groovesthe driving apparatus may also be a twisting apparatus with drivenrolls. In order to feed the roughing sections to the intermediate groupit would also be suflicient to provide the heating device with drivenrolls.

The single core rapid travel roughing group may be replaced in the caseof a two-core layout of the rolling mill train also by a rapid forgingmachine since such machines operate on the average with an output speedof 0.3 rn./ sec. which comes to about twice the input speed into theintermediate group, presuming a pass cross-section of 80 mm.

square for the intermediate group and a wire end speed of 50 m./sec.With a rapid forging machine one can go even higher in the passcross-section and come into the range of the continuous castingcross-sections which must be considerable for unkilled steel and be atleast e.g. 180 mm. square.

In the accompanying drawing two examples of a wire mill train accordingto the invention are schematically illustrated in Which? FIG. 1 is anexample of a four-core wire mill train with a single core roughing groupand FIG. 2 is a two-core mill train with a rapid forging machine.

The two examples of wire mill trains shown in the drawing have each aheating furnace 10, from which the billets arrive on a rolling track 12,and a high pressure spray-down device 14. In the example of FIG. 1 afive stand single core roughing group 16 with an H-V arrangement of thestands follows the high pressure spraydown device 14. At an intervalwhich corresponds to the free outlet distance of the roughing sectionsleaving the roughing group 16 is located an eight stand four-coreintermediate group 18, behind which the guide of the rolled stockbifurcates and the rolling operation is continued in two-coreintermediate groups 20, 21. Subsequently the cores 1, 2, 3 and 4 dividefor single core finishing rolling wherein each core finishing linecomprises a stand group 22 with two stands, a cropping shears 24, acooling line 26 and a nine stand wire end block 28. The single coreoperating stands are set up basically in an H-V arrangement. The wire isdistributed over horizontal working Edenborn coiler heads 30 onconveyors 32 for cooling and are subsequently gathered in a conventionalmanner into coils.

Behind the single core roughing group 16 is located a distributing guide34, a preferably gas heated heating device 36 and a four-core drivingapparatus 38 for feeding the roughing sections, which exit freely infront of the intermediate group 18, into the intermediate group 18. Theheating device 36 is made so wide that with a fourcore layout of themill train up to four roughing sections can be gathered in adjacentrelationship in the heating device over the distributing guide 34.

For a coil weight of 1500 kp. the rolling mill train according to FIG. 1permits a pass cross-section of 150 mm. square for the single coreroughing group 16 with a favorable billet length of 8.5 m. The fivestand roughing group 16 rolls the pass cross-section down to roughingsections of 30 m. length with a cross-section of mm. square. This is thepass cross-section for the four-core intermediate group 18 whose inputspeed, in consideration of a wire end speed 50 m./sec., equals 0.157m./sec. The output speed of the roughing group 16 amounts according tothe invention with a four-core wire mill train to at least the quadrupleof this input speed of 0.157 m./ sec. of the intermediate group 18 inorder to bring during single core operation of the roughing group theamount of rolled stock in the time unit in front of the intermediategroup 18 which may handle its four sizes in the time unit. The outletspeed of the roughing group 16 can also be started higher, e.g. with 1.5m./sec., which is favorable for the heat economy of the train. In thatcase the roughing group 16 may not be operated without stoppage but aroughing section may be fed into the heating furnace 36 only when agroove of the intermediate group 18 is vacant or is about to be vacated.In FIG. 1 the distributing guide 34 is located e.g. at the lower grooverow 4 and guides a roughing section 4' into an outer line of the heatingdevice 36. The groove 4 of the first stand of the intermediate group 18is about to be vacated so that the front end of the roughing billet 4'may be conducted into the driving apparatus 38 which introduces thiscore now with the low input speed of. the intermediate group 18 into thevacated fourth groove. The end of the roughing section 4' has mean-whileleft the roughing group 16.

Since with the pass of the roughing section 4 in the first stand of theintermediate group 18 or in the driving apparatus 38 the end of the 30m. long roughing billet should be in the heating device 36, the distancebetween the first stand of the intermediate group 18 and the front endof the heating device 36 is at least 30 m. Since the end of the roughingsection 4' has already left the last stand of the roughing group 16 whenits front end has been grasped by the driving apparatus 38 it isappropriate to provide between the distributing guide 34 and the heatingdevice 36 still another driving apparatus. Of course the feeding of theroughing sections after leaving the roughing group 16 can be assuredalso by the rolls of a roll track inside the heating device 36. As maybe seen from the roughing sections shown in hatched lines inside theheating device 36 the roughing billet of the core 1 is always completelypulled into the intermediate group 18. It is thus core 1 which is to besupplied next by the roughing group 16 with a roughing section and forthis purpose the distributing guide 34 is pivoted into the position 34'shown in hatched lines. The following core to be vacated is core 2 andsubsequently core 3 so that the distributing guide 34 is pivoted fromthe position 34 stepwise as far as the extended position and back again.The furnace supplies billets in the same rhythm as grooves are vacatedin the intermediate group 18.

The essence of the wire mill train according to FIG. 1 consits in thatin spit of the four-core layout one may roll out of a single furnacewith reasonable furnace width heavy coil weights because the problem ofthe heat consumption or of the low input speed in a continuous rollingprocess has been eliminated by the combination of a rapid travel singlecore roughing group with a multiple core heating device in front of theintermediate group 18. This heating device prevents not only the coolingof the rearward bar ends upon entering the intermediate group 18, but itheats up the last few bar ends of the roughing sections further with theaim that ultimately in the wire end blocks 28 the sections enter with aconstant momentary temperature into the first stand. This means highesttolerance maintenance of the finished product.

The two-core wire train according to FIG. 2 is based on the sameprinciple as the four-core train according to FIG. 1 with the differencethat the roughing group 16 is replaced by a rapid forging machine 40. Aspass crosssection may be taken billets of 180 mm. square whichcorresponds to an acceptable cross-section for continuously castunkilled steel. For a coil weight of 1500 kp. the billets would be 6 m.long. It is also possible to work here with the rapid forging machine 40down to roughing sections of 80 mm. square which are introduced over adistributing guide 34 alternately in adjacent relationship into atwo-core heating device 42 which is followed in accordance with FIG. 1by a driving apparatus 38 and an eight-stand intermediate group 44.Behind a further two-core stand group 46 with four stands are locatedtwo single core finishing lines each with a two-stand group 48, acropping shears 50, a cooling device 52 and with a wire end block 54. Itis to be understood that within the stand arrangement starting from theintermediate rolling operation there is nothing novel either in thetrain according to FIG. 1 or in the train according to FIG. 2.

Since in the example according to FIG. 2 the pass cross-section for theintermediate group 44 of 80 mm. square is the same as that in theexample according to FIG. 1 the input speed of the intermediate group 44with an end speed of 50 m./sec. is also the same at 0.157 mm./sec. Sincea rapid forging machine operates on the average with 0.3 m./sec. outletspeed which is not quite double the inlet speed of the intermediategroup 44 the core number of a rolling mill train according to FIG. 2with a rapid forging machine is limited to two. More cores would requirea multiple number of rapid forging machines.

In utilizing the invention for medium and high quality steel rollingtrains it is obvious that the aim of the invention is not the increaseof the coil weight but the rolling of particularly long bars which fromthe standpoint of. the heat economy raises the same problems as themanufacture of wire in heavy coil weights.

Since in the case of a medium or high quality rolling train according toFIGS. 1 or 2 the coiler heads 30 and the cooling conveyor belts 32 areto be replaced by cooling beds, it is indicated to subdivide the bars infront of the one or more cooling beds to reasonable cooling bed lengths,e.g. in that the cropping shears designated by 24 or 50 constitutesimultaneously dividing shears. These dividing shears could be mountedalso behind the finishing groups 28 and 54.

In applying the invention for medium and high quality rolling trains theinvention provides that the cropping and dividing shears are to bemounted in front of the intermediate groups 18 and 44, and one for eachcore. By means of these shears the roughing sections leaving the heatingtrough 36 are divided to such bar lengths or pass weights whichcorrespond to the cooling bed length of the predetermined finishingcross-section. Accordingly one obtains, in comparison with carrying outthe subdividing for example behind the finishing groups 28 or 54, aseries of advantages, namely:

( l) the end rolling speed is no longer limited by problems arising fromthe shears,

(2) no deformation of the finished bars by flying cut sections, thus aneasier further working particularly for iron sections,

(3) better utilization of the cooling bed surfaces since for eachfinishing dimension that particular roughing length may be sent into theintermediate and finishing rolling operation which corresponds to thefull cooling bed length,

(4) the interval between the bears which roll on in the cooling bedrange becomes larger than if finishing bars are subdivided whereby theroll-on track of the cooling beds is simplified.

It is to be understood that a multiple core wire train according to theinvention may be set up in a known manner with cooling beds as well aswith devices for producing coils either for each core or for a singlecore or for several cores.

What is claimed is:

1. A continuous multiple core rolling mill train for manufacturingrolled bar stock, comprising:

a furnace;

a single core roughing group operatively connected to said furnace;

a multiple core intermediate group spaced from said single core roughinggroup a distance greater than the maximum legnth of roughing sectionsleaving said roughing group permitting said roughing sections to exitfreely therefrom;

an elongated heating device operatively connected to said single coreroughing group for receiving said roughing sections one after the otherand means for distributing and feeding said roughing sections to thevacated grooves of said multiple intermediate group; and

single core finishing groups operatively connected to said multiple coreintermediate group.

2. A rolling mill as in claim 1, including a switchable distributingguide provided on the entry side heating device.

3. A rolling mill as in claim 2, said heating device being shorter thanthe length of said roughing sections and provided with means forreceiving said roughing sections except for the front end portionsthereof which protrude beyond the length of said furnace.

4. A rolling mill train as in claim 2, including a highpressurespray-down device operatively connected between said furnace and saidroughing group.

5. A method for continuously rolling bar stock, comprising:

heating billets; rollin-g said billets in a single core roughing group;collecting the roughing sections leaving said roughing group in aheating device preventing loss of temperature in the end portions ofsaid roughing sections;

feeding said roughing sections from said heating device into vacatedgrooves of a multiple core intermediate group; and

rolling said roughing sections in said intermediate group and in asubsequent single core finishing group.

6. A method as in claim 5, wherein said roughing group is operated at anoutput speed for the roughing sections leaving said roughing grouphigher relative to the inlet speed of the subsequent multiple coreintermediate group bv at least a multiple of the core number while theinlet References Cited UNITED STATES PATENTS 3,382,697 5/1968 Neumann72228 664,129 12/ 1900 Cronemeyer 72202 1,029,673 6/ 1912 Daniels 72202CHARLES W. LANHAM, Primary Examiner E. M. COMBS, Assistant Examiner US.Cl. X.R.

